The invention relates generally to umbrellas, and deals more particularly with a canopy rotator joint in an umbrella which joint allows the canopy to rotate during high winds and thereby avoid damage.
Winds can exert various types of forces on an umbrella canopy. One such force acts against the inner surface of the canopy longitudinally of the umbrella shaft, and can turn the umbrella canopy inside out. Many attempts have been made to reinforce the canopy against such reaction. For example, U.S. Pat. No. 3,032,047 to Wendorf discloses a storm umbrella which includes a peripheral cord secured to ends of outer ribs, as well as a series of guy assemblies attached to the ends of the outer ribs and to a sleeve on the center pole. This will apparently keep the ends of the ribs from being drawn outwardly to turn the umbrella inside out. Also, U.S. Pat. No. 4,300,582 to Desarno discloses another storm umbrella which includes an annular ring of flexible material around the periphery of the bottom, outer portion of the canopy between the ribs. The inner portion of the annular ring of flexible material is secured to a continuous cord of flexible, but not stretchable material. The outer portion of the ring of flexible material secures the fabric of the canopy as well as the ends of the ribs, and, together with the inner cord, prevents the entire structure from being turned inside out or otherwise damaged in high winds.
The winds can also exert a torsional force on the canopy which tends to twist the canopy and the ribs which support it. This may cause damage to the ribs and make it difficult for a person to hold the umbrella. The potential for damage to the ribs is exacerbated in an umbrella which has a canopy reinforced against turn-out because such a canopy traps the wind underneath the canopy.
Accordingly, a general object of the present invention is to provide an improvement to an umbrella which renders the umbrella less susceptible to damage caused by high winds.
A more specific object of the invention is to provide such an improvement which is usable with the reinforced umbrella described in U.S. Pat. No. 4,300,582 as well as other umbrellas with or without a reinforced canopy.